Osmeña yesterday said Roco was one of the brightest senators and could have been a good president.
"Mr. Roco had the potential of being a good president but he just didn't have the organizational skills to put it together," Osmeña said.
Roco, who challenged Arroyo in the last elections, died of cardiac arrest yesterday morning at St. Luke's Hospital in Quezon City. He was 63 and left behind his wife, six children, and four grandchildren.
Roco persisted in calling for reforms in government even during the time his health was already deteriorating.
Recently, he called for Arroyo's resignation in the wake of public allegations that she held conversations with a senior election official before the polls took place drawing suspicions that she rigged the results for her victory.